Lennox SL18XC1 Installation Instructions Manual page 13

STEP 8 -- EVACUATION
Evacuating the system of non-condensables is critical for proper operation of the unit. Non-condensables are defined as any
gas that will not condense under temperatures and pressures present during operation of an air conditioning system. Non-
condensables and water suction combine with refrigerant to produce substances that corrode copper piping and compres­
sor parts.
Danger of Equipment Damage. Avoid deep vacuum system operation. Do not use the system compressor to
evacuate a system. Extremely low vacuums can cause internal arcing and compressor failure. Damage caused by
deep vacuum system operation will void warranty.
LINE SET AND INDOOR COIL
CONNECT GAUGE SET
NOTE — Remove cores from service valves
(if not already done).
A Connect low side of manifold gauge set
with 1/4 SAE in-line tee to suction line
service valve
B Connect high side of manifold gauge
set to liquid line service valve
C Connect micron
connector on the 1/4 SAE in-line tee.
D Connect the vacuum pump (with
vacuum gauge) to the center port of the
manifold gauge set. The center port line
will be used later for both the HFC-410A
and nitrogen containers.
NITROGEN
HFC-410A
EVACUATE LINE SET AND INDOOR COIL
The unit is shipped with a factory refrigerant charge. The
liquid and suction line valves were closed after final testing
at the factory. Do not operate these valves until the line set
and indoor coil have been evacuated and leak checked, or
the charge is lost.
NOTE - Do not use any portion of the factory charge for
purging or leak testing. The factory charge is for filling the
system only after a complete evacuation and leak check
has been performed.
Line set and indoor coil should be evacuated using the rec­
ommended deep vacuum method of 500 microns. If deep
vacuum equipment is not available, the alternate triple
evacuation method may be used by following the specified
procedure.
gauge available
OUTDOOR
UNIT
VACUUM PUMP
WARNING
A34000 1/4 SAE TEE WITH
SWIVEL COUPLER
A
C
B
D
FIGURE 16
If vacuum must be interrupted during the evacuation pro­
cedure, always break vacuum with dry nitrogen.
The deep vacuum method requires a vacuum pump capa­
ble of pulling a vacuum to 500 microns and a vacuum
gauge capable of accurately measuring this vacuum level.
The deep vacuum method is the most positive way of as­
suring a system is free of air and water.
Watch the vacuum gauge as the system is pulling down.
The response of the gauge is an indicator of the condition
of the system (refer to figure 17).
With no leaks in the system, allow the vacuum pump to run
for 30 minutes minimum at the deep vacuum level.
Page 13
LOW
500
MICRON
GAUGE
TO SUCTION
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
RECOMMEND
MINIMUM 3/8" HOSE
Deep Vacuum Method
MANIFOLD
GAUGE SET
HIGH
SL18XC1 SERIES